AEC From the Ground Up-IFCs in Action

The 3D object exchange format of choice for BIM buildings.

At The Aec/St Convention in Washington, D.C., in December, I noted quite a bit of interest in BIM (building information modeling) and the IFC (Industry Foundation Class) format. BIM software is what the AEC industry is turning to for the creation of building designs, and it appears that the IFC format will be the open downstream transfer format for that information. NIBS (National Institute of Building Standards; www.nibs.org), the group creating the new National BIM Standard, has decided that IFC is the best method for information transfer, and the GSA (General Services Administration) has mandated that, starting in July, the delivery of IFC-transferable BIM data will be required for the preliminary design phase of all of its new fiscal year 2006 projects.

What are IFCs?

The IFC system is a data representation standard and file format used to define architectural and construction-related CAD graphic data as 3D real-world objects. Its main purpose is to provide architects and engineers with the ability to exchange data between CAD tools, cost estimation systems and other construction-related applications. IFC provides a set of definitions for all object element types encountered in the building industry and a text-based structure for storing those definitions in a data file. IFC uses a plain text file, while CAD developers store data in product-specific binary file formats that best suit their own systems. To standardize 3D object data, developers provide Save As IFC and Import IFC commands, which map the IFC object definitions to their CAD system's 3D representations of these objects.

Modern BIM systems are able to create rich internal representations of building components, and the IFC format adds a common language for transferring that information between different BIM applications while maintaining its meaning. This reduces the need to remodel the same building in each different application.

This nonproprietary format has been developed by the IAI (International Alliance for Interoperability; www.iai-na.org/). This global consortium of commercial companies and research organizations was founded in 1995. Its North American chapter is now part of NIBS. According to the IAI, the IFC model is intended to support interoperability across individual, discipline-specific applications used to design, construct and operate buildings by capturing information about all aspects of a building throughout its lifecycle. It was specifically developed as a means to exchange data between model-based applications in the AEC and FM industries.

Spreading support

At this writing, Autodesk's Architectural Desktop and Revit Building, Bentley Architecture, Graphisoft's ArchiCAD and Nemetschek's Allplan have implemented IFC capability. VectorWorks IFC implementation will be available later this year. Now that these BIM applications support IFC export, other software vendors are beginning to develop solutions that use BIM data created during the building design process.

Below is a sampling of applications that can use and manipulate data created in BIM software programs. All transfer their 3D information using the IFC file format schema.

NavisWorks

Roamer JS is the hub of the NavisWorks JetStream design review solution. It delivers interactive visualization and smooth real-time walkthrough and review of even the largest and most complex 3D models. It's compatible with most popular 3D design and laser scan file formats, and with the addition of IFC import, can open models quickly for walkthrough and review of geometry and object information. The Clash Detective JS plug-in eliminates manual checking of object clashes. It finds and manages both hard and clearance clashes. Geometry created in different 3D design applications can be reviewed together and automatically checked against each other. Clash test results are stored and merged to create a complete record of all interferences found. Users can set up their own clash test rules and produce detailed reports as HTML documents.

Solibri Model Checker v3

Think of Solibri Model Checker as a spell checker for virtual models (figure 1). The program analyzes building models for integrity, quality and physical security. It checks for potential flaws and weaknesses in the design, highlights clashing components and determines whether the model complies with building codes and the organization's own best practices. It also helps users extract information from the building model for use in downstream applications such as quantity and cost calculation. The latest version of Solibri Model Checker highlights the source of problems by making the rest of the building invisible and illustrates problematic components within the footprint of the wall plan to make them easy to locate. Because this software is user customizable, it can check for code requirements such as egress distance and door size per occupant load in a given space. According to the developer, the GSA will use this software to check the correctness of the BIM data it requires from its architectural consultants.

YIT COVE and Tarmo, Graphisoft Constructor and Estimator

YIT, a Nordic construction and services company, developed two IFC-based programs to work with Graphisoft models. COVE is a tool for model-based information management of the construction process. It uses IFCs to import information from various design and other programs into a single 3D construction model. TARMO cost estimation software is able to integrate the construction schedule to create a 4D model. YIT has used COVE in production since 1999 on more than 200 projects. In 2004 YIT sold rights to develop and market the product to Graphisoft. At the same time, the companies agreed on a strategic partnership for further development of product model technology into commercial software. The commercial tool based on COVE is called Graphisoft Constructor 2005, and the one based on TARMO is Graphisoft Estimator 2005 (figure 2).

Figure 2. Graphisoft s Constructor 2005 and Estimator 2005 use IFC import to reuse building information in a construction model.

Data Design System Building Services Partner

Available primarily in Europe, Data Design System's Building Services Partner is designed to facilitate model-based collaboration with other disciplines using IFC files or an advanced IFC model server environment. The company also developed an IFC file viewer that opens and displays IFC models created by applications such as DDS Building Services Partner. This tool is available for download free at the company Web site.

DDS Partner is an integrated system for planning, production and control of HVAC, piping and electrical system documentation. It's a proficient planning tool not only for the professional consulting engineer, but also installation contractors and ventilation specialists. Facility managers can also gain productivity using the system. DDS HVAC Partner delivers integrated calculations for building heat loss, duct sizing and pressure loss. Its tools handle pipe network sizing, under-floor heating design, and quantity extraction. Electrical Partner's lighting calculations help users develop effective lighting schemes for projects. Those who need a more advanced lighting solution can use Dialux or Relux software directly with Electrical Partner. This product's built-in CAD engine has DXF/DWG support as well as IFC integration.

ideCAD Structural 5

Developed in Turkey for structural designers of tall buildings, ideCAD Structural 5 is integrated analysis, design and detailing software for reinforced concrete constructions. It covers all relevant phases, from dynamic analyses to design of reinforced concrete cross-sections. Reinforcement details are automatically generated. A joint platform on the Web allows collaboration between structural engineers and architects. Users design and plan using real components such as walls, windows, columns, beams and foundations. A 3D user interface displays both 3D building models and their related analysis results for evaluation. This integrated visualization ability supports not only creation of renderings and animations, but also smooth and simple project planning. Static calculation and reinforced-concrete measurements are carried out on the basis of the 3D calculation model. Compatibility with IFC, DXF and DWG enables exchange of data with other CAD programs (figure 3).

Figure 3. IdeCAD is a stand-alone CAD program that uses IFC support to exchange data with other CAD programs.

Just Starting

Today downstream IFC-based applications are still in their infancy. The following site lists software certified by the IAI: www.bauwesen.fh-muenchen.de/iai/ImplementationOverview.htm. The reality as I see it, and as I mentioned in my November 2005 column (http://aec.cadalyst.com/1105aec/), is that the main benefit of BIM software currently comes from increased productivity in creating construction documents. Although the downstream segment of the industry is just getting started, I anticipate a plethora of software that will eventually integrate, collate and extrapolate BIM data in ways that are not even imagined today. These new solutions—receiving and transferring their data through future versions of the IFC format—will surely make the AEC industry more productive and offer new profit streams for professionals using them.

About the Author: AIA

About the Author: H. Edward Goldberg

In her easy-to-follow, friendly style, long-time Cadalyst contributing editor and Autodesk Technical Evangelist Lynn Allen guides you through a new feature or time-saving trick in every episode of her popular AutoCAD video tips. Subscribe to the free Cadalyst Video Picks newsletter and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!